1. Introduction

Efficient visualization of graphs and their usage for data analysis implies

the manipulation of the structure of the graph

the extraction of parts of it

association of values to a graph's elements (nodes and edges)

the computation of intrinsic parameters (parameters derived from a graph's structure,
e.g. in a filesystem graph (directory tree): number of files in a directory, can be computed by counting
outgoing edges)

This chapter describes the Tulip data structure that takes into account all the requirement
of a graph visualization system. For each part we describe the general principle and
then we give examples explaining how to do it with the Tulip library.